He must have been named after his grandfather. - Его, должно быть, назвали в честь дедушки.
He must have been named after his grandfather.
Его, должно быть, назвали в честь дедушки.
They must have made a mistake. - Они, должно быть, ошиблись.
They must have made a mistake.
Они, должно быть, ошиблись.